Polishing composition and method for high silicon nitride to silicon oxide removal rate ratios
AssigneeCabot Microelectronics Corporation
InventorsJeffrey M. Dysard, Timothy P. Johns
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Abstract
The invention provides a chemical-mechanical polishing composition comprising a cationic abrasive, a cationic polymer, an inorganic halide salt, and an aqueous carrier. The invention further provides a method of chemically-mechanically polishing a substrate with the aforementioned polishing composition. The polishing composition exhibits selectivity for removal of silicon nitride over removal of silicon oxide and polysilicon.
Claims11
A chemical-mechanical polishing (CMP) method for polishing a substrate, the method comprising the steps of:
- (a) contacting a surface of a substrate comprising silicon nitride, silicon dioxide, and polysilicon, with a polishing pad and a CMP composition having a pH of about 7 or less, the CMP composition comprising a cationic abrasive, a cationic polymer, an inorganic halide salt, an aqueous carrier;
- (b) causing relative motion between the polishing pad and the substrate with a portion of the CMP composition therebetween to selectively abrade silicon nitride from the surface relative to silicon dioxide and polysilicon.
A chemical-mechanical polishing (CMP) method for selectively abrading silicon nitride in the presence of silicon dioxide, the method comprising the steps of
- (a) contacting a surface of a substrate comprising silicon nitride and silicon dioxide with a polishing pad and a CMP composition having a pH of about 7 or less, the CMP composition comprising a cationic abrasive, a cationic polymer, an inorganic halide salt, an aqueous carrier;
- (b) causing relative motion between the polishing pad and the substrate with a portion of the CMP composition therebetween to abrade silicon nitride from the surface at a removal rate in the range of about 6 to about 60 times the rate at which silicon dioxide is abraded from the surface.
A chemical-mechanical polishing (CMP) method for selectively abrading silicon nitride in the presence of polysilicon, the method comprising the steps of:
- (a) contacting a surface of a substrate comprising silicon nitride and polysilicon with a polishing pad and a CMP composition having a pH of about 7 or less, the CMP composition comprising a cationic abrasive, a cationic polymer, an inorganic halide salt, an aqueous carrier;
- (b) causing relative motion between the polishing pad and the substrate with a portion of the CMP composition therebetween to abrade silicon nitride from the surface at a removal rate exceeding the rate at which polysilicon is abraded from the surface.
Dependencies are inferred from the claim text.